Feeding intolerance is very common especially in the very low birth-weight infants (VLBW) infants. This is a major concern for neonatologists, and controversy exists regarding how fast to advance enteral feedings. Current decisions to feed the premature infants are based on indicators such as gastric residuals, abdominal circumference and clinical appearance. These are highly subjective and provide poor evidence about feeding readiness. In fact, gastric residual measurements may have some unwanted side effects such as gastric mucosal disruption and removal of active enzymes and gastric acid. Reliance on such subjective clinical judgment rather than objective criteria often results in overly aggressive feeding the infants with high risk of developing necrotizing enterocolitis (NEC), or underfeeding that can lead to growth failure, atrophy of the bowel, increased inflammatory responses, and an increased likelihood for the development of sepsis.
An important task is to clarify whether the neonatal gastrointestinal (GI) tract has matured adequately for accepting feeding advancements. Objective and scientific investigations are necessary to clarify if the signs of feeding intolerance are predictive of NEC or due to normal maturation patterns. For the infants who have had surgery for bowel disease such as gastroschisis and necrotizing enterocolitis (NEC), metabolic demands are increased due to overlapping requirements for growth and recovery. A means for determining enteral feeding readiness is crucial for these infants.
Premature feeding attempts may exacerbate feeding intolerance, while lack of enteral feedings will prolong intravenous nutrition and its associated complications. Current decisions on when to introduce feedings in these infants are based on clinical criteria such as stool passage and presence of bowel sounds supported by conventional auscultation technique. Many infants (i.e. those with gastroschisis) have never been fed and have little stool to pass. Presence or absence of bowel sounds is not very reliable for the prediction of feeding readiness in these infants. Prediction may be improved by using alternative non-invasive investigations of bowel motility or more rigorous objective investigation of bowel sounds. The ability to accurately discern the babies who can be safely fed and have their enteral feedings increased versus the ones who cannot would be a critical advance in neonatal intensive care. Methods currently used in the neonatal GI evaluation include plain radiography, which is readily applicable and valuable in detecting NEC, bowel performation, and bowel obstruction. However, the information that can be obtained regarding gut motility and feeding readiness using this method is very limited. While contrast studies can provide some functional information about gastric emptying or intestinal transit that is derived from anatomic delineation, radiography is limited in that it is a qualitative assessment method and produces planar and snapshot images of a single point in time. Scintigraphy, which is not a widely used method in infants, can also be used for motility research. A gamma camera is used to image radionuclide tracers in GI transit studies. It is limited, however, by poor image resolution, interpretational difficulty for overlapping intestine, and practical difficulty of moving patients to the testing site. Radiation exposure is a critical drawback for both radiography and scintigraphy.
Therefore, current technologies are limited in validation, practical application and patient safety. Therefore, the evaluation of feeding readiness in premature infants using these methods is less than satisfactory, and continuing efforts for developing better assessment modalities are needed.